Field of the Invention
The present invention relates to electrical connectors, and has particular relevance to electrical connectors having electrical contacts which are small and/or fragile and/or subject to damage and protection for the contacts and/or the electrical interconnection is desired. The present invention thus relates to such electrical connectors as zero-insertion-force (ZIF) connectors, connectors with surface emanating springs such as Neoconix PCBeam™ connectors, pogo pin connectors and sockets, cantilever beam connectors, spiral spring connectors, land grid array connectors, and two-piece stacked (“mezzanine”) board-to-board connectors, as well as connectors for other interconnection applications. It has particular relevance to those applications in which a compressive force is applied to actuate an electrical and mechanical interconnection between two electronic components.
Background Art
Various electrical connectors are known in the art such as ZIF (zero insertion force) electrical connectors, connectors with surface-emanating springs (such as the PC-Beam electrical connectors from Neoconix, the assignee of the present invention), two-piece stacked board-to-board connectors, and other similar electrical connectors. These electrical connectors provide electrical interconnection between electronic components within an electronic system, typically when a compressive force is applied between the connector and one or more circuit members to provide electrical and mechanical interconnections between two circuit members or electronic components, or between the connector and one other electronic component. Electronic components, as defined here, can include circuit members such as printed circuit boards, flexible printed circuits, modules, integrated circuits, integrated circuit package substrates, memory modules, multichip modules, mother boards, daughter cards, main logic boards, memory boards, passive components, active devices, sockets, connectors, and the like.
In one typical application of an electrical connector, for interconnection of two circuit members, such as interconnection of a first rigid printed circuit board to a second rigid printed circuit board or to a first flexible printed circuit, movable and electrically conductive spring elements of an electrical connector serve as electrical contacts, and are actuated by compressing them primarily in a vertical (Z) direction (perpendicular to the mating surface of the circuit member) to electrically and mechanically connect them to electrically conductive circuit paths (e.g. traces, pads, circuits, or other spring elements) on the circuit members, whereby when actuated, the spring elements provide an electrical interconnection to the electrically conductive circuit paths.
In such a connector system, the contact springs may at times be exposed to external forces which can cause damage, such as during handling, testing, inspection, and assembly into an electronic device. For this reason, in some connectors such as two piece ‘mezzanine connectors’ or ZIF connectors with molded plastic housings, the contact springs may be recessed into the housings. In other words, they may not protrude out from the highest or outermost surfaces of the connector. However, because these housings are highly rigid, this type of protective structure adds to the thickness of the connector, which can be a detriment in miniaturized electronic systems such as mobile consumer products. This type of design may also require a portion of one or both of the mating members to protrude into the recess in the connector in order to make electrical connection, such as in the case of a stacked board to board connector with a header and a socket or receptacle, and the case of a flexible printed circuit connecting to a ZIF connector mounted on a printed circuit board. In some of the two piece stacked connectors, the contacts in the receptacle are recessed and hence somewhat protected, whereas the contacts in the header are not recessed and hence may not be as effectively protected from damage. In a connector with surface emanating contacts or other non-recessed contacts, significant over-compression, upward displacement, or lateral displacement of the electrical contacts can cause damage to the electrical contacts. Some electrical contacts are susceptible to damage such as scratching or contamination, or to plastic yielding due to excessive bending, twisting, lifting, over-compression or other rough handling. In some cases, such damage reduces the effectiveness of the electrical contacts; in severe cases, the electrical contacts may become unusable or their performance compromised. As connectors become more miniaturized to allow smaller electronic systems, the contact springs will likely be required to become smaller as well, and as such they may become more fragile.
Further, in some applications moisture or liquids may be present in the vicinity of the electrical connector, during functional use of the connector in the ultimate application. It is desirable to avoid fluid or moisture ingress at the point where the electrical interconnection occurs (the interfaces between the electrical spring contacts of the connector and the mating conductive circuits on the mating circuit member) to avoid degradation of the integrity of the interconnection from oxidation or other moisture-induced damage to the contact or mating conductive circuit element. Further, when an electronic device, such as a mobile phone, is powered on, and water or other conductive liquid penetrates to the electrical connections of a connector, a short circuit can occur which can interrupt the function of the device, and/or may cause permanent damage to critical components of the system.
Other limitations and disadvantages of the present electrical connectors will be apparent to someone of ordinary skill in the art in view of the description of the present invention which follows in this document.